def install(self):
        # get content type.
        if is_file(self.download_url):
            path = fileurl_to_path(self.download_url)
            self.content_type = mimetypes.guess_type(path)[0]
        else:
            headerinfo = Downloader.read_head_info(self.download_url)
            self.content_type = headerinfo['content-type']
        if is_html(self.content_type):
            # note: maybe got 404 or 503 http status code.
            logger.error("Invalid content-type: `%s`" % self.content_type)
            return

        if os.path.isdir(self.install_dir):
            logger.info("You have already installed `%s`" % self.pkg.name)
            return

        self.download_and_extract()
        logger.info("\nThis could take a while. You can run the following command on another shell to track the status:")
        logger.info("  tail -f %s\n" % self.logfile)
        logger.info("Installing %s into %s" % (self.pkg.name, self.install_dir))
        try:
            self.patch()
            self.configure()
            self.make()
            self.make_install()
        except Exception:
            import traceback
            traceback.print_exc()
            rm_r(self.install_dir)
            logger.error("Failed to install %s. Check %s to see why." % (self.pkg.name, self.logfile))
            sys.exit(1)
        self.symlink()
        logger.info("\nInstalled %(pkgname)s successfully." % {"pkgname": self.pkg.name})

    def install(self):
        # check if java is installed
        r = subprocess.call("command -v java > /dev/null", shell=True)
        if r != 0:
            logger.error("Jython requires Java to be installed, but the 'java' command was not found in the path.")
            return

        # get content type.
        if is_file(self.download_url):
            path = fileurl_to_path(self.download_url)
            self.content_type = mimetypes.guess_type(path)[0]
        else:
            try:
                headerinfo = Downloader.read_head_info(self.download_url)
            except DownloadError:
                self.content_type = None
            else:
                self.content_type = headerinfo['content-type']
        if is_html(self.content_type):
            # note: maybe got 404 or 503 http status code.
            logger.error("Invalid content-type: `%s`" % self.content_type)
            return

        self.download()
        logger.info("\nThis could take a while. You can run the following command on another shell to track the status:")
        logger.info("  tail -f %s\n" % self.logfile)
        logger.info("Installing %s into %s" % (self.pkg.name, self.install_dir))
        cmd = 'java -jar %s -s -d %s' % (self.download_file, self.install_dir)
        s = Subprocess(log=self.logfile, verbose=self.options.verbose)
        s.check_call(cmd)
        self.symlink()
        logger.info("\nInstalled %(pkgname)s successfully." % {"pkgname": self.pkg.name})

    def install(self):
        # cleanup
        if os.path.isdir(self.build_dir):
            shutil.rmtree(self.build_dir)

        # get content type.
        if is_file(self.download_url):
            path = fileurl_to_path(self.download_url)
            self.content_type = mimetypes.guess_type(path)[0]
        else:
            headerinfo = Downloader.read_head_info(self.download_url)
            self.content_type = headerinfo['content-type']
        if is_html(self.content_type):
            # note: maybe got 404 or 503 http status code.
            logger.error("Invalid content-type: `%s`" % self.content_type)
            return

        if os.path.isdir(self.install_dir):
            logger.info("You have already installed `%s`" % self.pkg.name)
            return

        self.download_and_extract()
        logger.info("\nThis could take a while. You can run the following command on another shell to track the status:")
        logger.info("  tail -f %s\n" % self.logfile)
        logger.info("Installing %s into %s" % (self.pkg.name, self.install_dir))
        shutil.copytree(self.build_dir, self.install_dir)
        self.symlink()
        logger.info("\nInstalled %(pkgname)s successfully." % {"pkgname": self.pkg.name})